Mechanisms of void nucleation on neat and Glass Syntactic PolyPropylene using in situ synchrotron radiation tomography

The mechanisms of void nucleation of a hollow glass syntactic foam during tensile loading were studied in depth. Flat-notched geometries, cut-out from neat and Glass Syntactic PolyPropylene (GSPP), were investigated by in situ microtomography. Notched specimens with two notch root radii, 4 mm and 0.15 mm named respectively N 4 and N 0 . 15 , to set initial triaxial stress state in the minimum cross section, were observed. Tomographic data sets, with a resolution of 1 . 3 μ m , from stepwise tensile loading, at the SOLEIL synchrotron radiation facilities, were retrieved from the notched zone. In addition, they allowed gathering both the width and thickness evolution in the minimum cross section, and the notch opening displacement during the tests. In line with literature, neat PolyPropylene (PP) showed crazes concentration at the specimen core in N 4 specimen, whereas, in N 0 . 15 specimen, they were located at the notch root. In isolated Hollow Glass Microspheres (HGM), mechanisms of crazing and debonding were correspondingly highlighted in the PP matrix and at the poles of HGM. Finally, in GSPP, decohesion follows the same trend as in neat PP, i.e. at the specimen core and near the notch, respectively in N 4 and in N 0 . 15 geometry. Scenarios of void nucleation and propagation were outlined. The initiation of the brittle crack in the GSPP is mainly due to the matrix-HGM decohesion followed by the coalescence of near neighbouring caps. • Void nucleation on hollow glass syntactic foam by in situ tensile loading was studied. • Crazing and debonding interaction was seen in resin-embedded isolated filler. • Brittle crack in GSPP is mainly due to the matrix-HGM decohesion. • Coalescence between crazes and decohesion caps during tensile loading is highlighted.